It is well known to provide a fluid dispenser in which fluid is dispensed via a nozzle or orifice upon the application of a force by a user to a pump dispenser. Such devices are generally arranged with a reservoir containing several doses of a fluid formulation to be dispensed by sequential metered pump actuations. An example of a pump action spray is shown and described in U.S. Pat. No. 4,946,069.
A hand-held, manually operable intra-nasal fluid medicament dispenser is disclosed in WO-A-03/095007, the entire content of which is hereby incorporated herein by reference. The dispenser has a housing which houses a fluid discharge device having a compression pump mounted on a container, which contains the medicament. The housing has at least one finger-operable side lever, which is movable inwardly with respect to the housing to cam the container upwardly in the housing to cause the pump to compress and pump a dose of the medicament out of a pump stem through a nasal nozzle of the housing. In an embodiment shown in FIGS. 19, 19a and 19b, a pair of opposed side levers co-operate with a collar mounted on the neck of the container. The collar provides cam follower surfaces, which ride over cam surfaces of the levers when the levers are moved inwardly. The cam follower surfaces comprise sections, which are inclined at different angles to the direction (axis) of cam movement of the fluid discharge device. The steeper sections provide the dispenser with a commitment feature. In other words, only upon application of at least a minimum finger force to the side levers will the levers be able to overcome the steeper cam follower surface sections. The magnitude of this force, coupled with the change of angle of the cam follower surfaces to the shallower sections, ensures that each lever slides rapidly over the cam follower surfaces once the steeper cam follower surface sections are overcome thereby providing for reliable compression of the compression pump and atomisation of the medicament.
Applicant's co-pending PCT Patent Application no. PCT/GB2005/000944, the entire content of which is hereby incorporated herein by reference, describes another hand-held, manually operable intra-nasal fluid medicament dispenser, in which in a dispensing action, a cam surface of a finger-operable side lever co-operates with a cam follower surface of a collar mounted on the neck of a container to cam the container along an axis to pump fluid medicament therefrom. The cam surface of the lever has a commitment section, oriented at a first angle to the axis, and an adjacent drive section, which is oriented at a second angle to the axis, which is greater than the first angle. In use, the cam follower surface successively rides over the commitment and drive sections of the cam surface. The commitment section thereof is planar.
The Applicant has now found that the interaction of the cam follower surface on the collar with the cam surface of the lever, and hence ease of fluid dispensing, is assisted where the commitment section of the cam surface has an arcuate form. In particular, for smooth actuation of the dispenser it has been found to be beneficial for both the commitment and drive sections to have arcuate forms, wherein those arcuate forms are of opposite arcuate character (e.g. one concave, and the other convex in character).